基于电导电极的肥液浓度在线检测仪设计与实现  

Design and Implement of an On-line Detector for Fertilizer Solution Concentration based on Conductivity Electrode

作　　者：李加念[1] 倪慧娜[2] 马燕[1] 冯瑞[1] 

机构地区：[1]昆明理工大学现代农业工程学院,云南昆明650500 [2]华南农业大学工程学院,广东广州510642

出　　处：《安徽农业科学》2014年第12期3465-3467,3470,共4页Journal of Anhui Agricultural Sciences

基　　金：昆明理工大学省级人培项目(KKSY201323003);大学生创新训练项目(201310674245)

摘　　要：[目的]为能实时检测灌溉施肥系统进行水肥自动混合时的肥液浓度。[方法]基于电导电极设计了一种以9 V电池供电的肥液浓度在线检测仪,通过测量肥液电导率间接实现肥液浓度的测量,测量结果可通过显示器直接显示,还可通过SPI接口输出至水肥自动混合控制器。为尽量降低极化效应的影响,试验确定了以幅值为±3.5 V的方波信号作为电导电极的激励源。该检测仪具有温度自动补偿和量程自动切换功能,并通过试验确定了测量量程范围的划分及各个小量程对应的分压电阻与方波激励信号频率。[结果]在农业上,常用的0.1%~1.0%施肥浓度范围内,对检测仪进行了试验验证,其平均相对误差为2.77%。[结论]该检测仪能满足实际应用要求。[ Objective] The research aimed to realize real-time detecting of fertilizer solution concentration for automatic mixing of water and fertilizer in fertigation systems. [ Method] An on-line detector powered by a 9 V battery was designed for detecting fertilizer solution concentra- tion which could be realized indirectly by using a conductivity electrode to detect fertilizer solution conductivity. The measured results could be displayed on the monitor and sent to the automatic mixing controller for water and fertilizer. In order to reduce the influence of polarization effect as possible, a square wave signal whose amplitude was ＋ 3.5 V had been selected as excitation source for the conductivity electrode through experiments. The detector had the functions of automatic temperature compensation and measuring range automatic switch, the measur- ing range had been divided into several small scale range by taking experiments, so did the configuration of divider resistor and frequency of square wave for each small scale range. [ Result] Verification test had been performed for the detector in a series of fertilizer solution whose concentration range was 0.1% - 1.0% which was the comr^on used fertilizing concentration range in agriculture, and the tested results showed that mean relative error of the detector was 2.77%. [ ConClusion] Test detector could meet the requirement of practical application.

关 键 词：肥料 溶液 肥料浓度 检测 电导率 

分 类 号：S126[农业科学—农业基础科学]